One of the fundamental lessons of the Sept. 11 tragedy was that our government carried a share of blame for the failure to stop the attacks.

Not because it was asleep at the switch or ignorant of the dangers that al-Qaida posed, but because the agencies charged with our safety did not share what they knew, either up and down the chain of command or with each other. The attacks were preventable with shared information.

This insight was highlighted in the report of the Sept. 11 Commission — on which I served — and became a key driver of the reforms instituted by the U.S. intelligence community over the last dozen years.

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